Although visually outdated at the time of its release, ZZT became fairly popular because of its integration of an object-oriented scripting language known as ZZT-OOP. The language allowed community involvement that extended beyond simply creating level terrain with the built-in editor.
Originally ZZT was shareware, with only one of the four level-sets or "worlds" released without payment. The level released with the shareware copy is called "Town of ZZT". The shareware versions also included "Demo of ZZT", which displayed the basic features of ZZT worlds, and "Tour of ZZT", which allowed the player to view select rooms (some playable) of the four worlds. Three different versions of shareware ZZT were released, with three corresponding registered versions. With about 30,000 registrations worldwide, ZZT was successful enough to finance the production of Jill of the Jungle. As the game became obsolete it became freeware, however, with all four worlds of the registered version released for free. The worlds are: "Town of ZZT", "Caves of ZZT", "Dungeons of ZZT", and "City of ZZT".
In the newsletters for the registered version of ZZT, it is apparent that Sweeney initially had not expected the editor to become the most popular feature of his game. Fans' letters to him quickly established this, and Sweeney responded by encouraging registered users to make their own worlds and submit them to him. The best material from these was released in The Best of ZZT.
Gameplay of ZZT is very simple. The player is controlled by the four cursor keys, and the shift key and a cursor key pressed will shoot a bullet (if the player has ammo). Items that can be picked up include: ammo (each magazine holds five rounds), gems (used for currency in most games), torches (used by pressing the T key in darkened rooms, lighting a small area around the player, that moves as the player does), and energizers that give the player temporary invincibility. Enemies include lions (randomly moving monsters, that may follow the player), tigers (randomly moving monsters that fire bullets), ruffians (monsters that chase the player, then rest, then repeat), bears, slimes, and spinning guns.
Third-party worlds for ZZT are diverse, ranging from shoot 'em ups to complex role-playing video game to a Lemmings clone (Zem). Other games have been inspired by ZZT, such as MegaZeux and ZZT's sequel, Super ZZT, the latter being widely criticized for lacking an easily accessible editor function.
As of 2009, ZZT was still for sale through mail order, according to Sweeney in a Gamasutra interview. The last copy was distributed in late 2013.
Entry from Wikipedia